* s3: add s3:ExistingObjectTag condition support in policy engine
Add support for s3:ExistingObjectTag/<tag-key> condition keys in bucket
policies, allowing access control based on object tags.
Changes:
- Add ObjectEntry field to PolicyEvaluationArgs (entry.Extended metadata)
- Update EvaluateConditions to handle s3:ExistingObjectTag/<key> format
- Extract tag value from entry metadata using X-Amz-Tagging-<key> prefix
This enables policies like:
{
"Condition": {
"StringEquals": {
"s3:ExistingObjectTag/status": ["public"]
}
}
}
Fixes: https://github.com/seaweedfs/seaweedfs/issues/7447
* s3: update EvaluatePolicy to accept object entry for tag conditions
Update BucketPolicyEngine.EvaluatePolicy to accept objectEntry parameter
(entry.Extended metadata) for evaluating tag-based policy conditions.
Changes:
- Add objectEntry parameter to EvaluatePolicy method
- Update callers in auth_credentials.go and s3api_bucket_handlers.go
- Pass nil for objectEntry in auth layer (entry fetched later in handlers)
For tag-based conditions to work, handlers should call EvaluatePolicy
with the object's entry.Extended after fetching the entry from filer.
* s3: add tests for s3:ExistingObjectTag policy conditions
Add comprehensive tests for object tag-based policy conditions:
- TestExistingObjectTagCondition: Basic tag matching scenarios
- Matching/non-matching tag values
- Missing tags, no tags, empty tags
- Multiple tags with one matching
- TestExistingObjectTagConditionMultipleTags: Multiple tag conditions
- Both tags match
- Only one tag matches
- TestExistingObjectTagDenyPolicy: Deny policies with tag conditions
- Default allow without tag
- Deny when specific tag present
* s3: document s3:ExistingObjectTag support and feature status
Update policy engine documentation:
- Add s3:ExistingObjectTag/<tag-key> to supported condition keys
- Add 'Object Tag-Based Access Control' section with examples
- Add 'Feature Status' section with implemented and planned features
Planned features for future implementation:
- s3:RequestObjectTag/<key>
- s3:RequestObjectTagKeys
- s3:x-amz-server-side-encryption
- Cross-account access
* Implement tag-based policy re-check in handlers
- Add checkPolicyWithEntry helper to S3ApiServer for handlers to re-check
policy after fetching object entry (for s3:ExistingObjectTag conditions)
- Add HasPolicyForBucket method to policy engine for efficient check
- Integrate policy re-check in GetObjectHandler after entry is fetched
- Integrate policy re-check in HeadObjectHandler after entry is fetched
- Update auth_credentials.go comments to explain two-phase evaluation
- Update documentation with supported operations for tag-based conditions
This implements 'Approach 1' where handlers re-check the policy with
the object entry after fetching it, allowing tag-based conditions to
be properly evaluated.
* Add integration tests for s3:ExistingObjectTag conditions
- Add TestCheckPolicyWithEntry: tests checkPolicyWithEntry helper with various
tag scenarios (matching tags, non-matching tags, empty entry, nil entry)
- Add TestCheckPolicyWithEntryNoPolicyForBucket: tests early return when no policy
- Add TestCheckPolicyWithEntryNilPolicyEngine: tests nil engine handling
- Add TestCheckPolicyWithEntryDenyPolicy: tests deny policies with tag conditions
- Add TestHasPolicyForBucket: tests HasPolicyForBucket method
These tests cover the Phase 2 policy evaluation with object entry metadata,
ensuring tag-based conditions are properly evaluated.
* Address code review nitpicks
- Remove unused extractObjectTags placeholder function (engine.go)
- Add clarifying comment about s3:ExistingObjectTag/<key> evaluation
- Consolidate duplicate tag-based examples in README
- Factor out tagsToEntry helper to package level in tests
* Address code review feedback
- Fix unsafe type assertions in GetObjectHandler and HeadObjectHandler
when getting identity from context (properly handle type assertion failure)
- Extract getConditionContextValue helper to eliminate duplicated logic
between EvaluateConditions and EvaluateConditionsLegacy
- Ensure consistent handling of missing condition keys (always return
empty slice)
* Fix GetObjectHandler to match HeadObjectHandler pattern
Add safety check for nil objectEntryForSSE before tag-based policy
evaluation, ensuring tag-based conditions are always evaluated rather
than silently skipped if entry is unexpectedly nil.
Addresses review comment from Copilot.
* Fix HeadObject action name in docs for consistency
Change 'HeadObject' to 's3:HeadObject' to match other action names.
* Extract recheckPolicyWithObjectEntry helper to reduce duplication
Move the repeated identity extraction and policy re-check logic from
GetObjectHandler and HeadObjectHandler into a shared helper method.
* Add validation for empty tag key in s3:ExistingObjectTag condition
Prevent potential issues with malformed policies containing
s3:ExistingObjectTag/ (empty tag key after slash).
Chris Lu
d6d893c8c3